Zeolites are a commercially important class of crystalline materials. They have distinct crystal structures with ordered pore structures which are demonstrated by distinct X-ray diffraction patterns. The crystal structure defines cavities and pores which are characteristic of the different species.
Zeolites identified by the International Zeolite Associate as having the structure code STF are known. For example, the zeolite known as SSZ-35 is a known crystalline STF material. U.S. Pat. No. 5,316,753 discloses the preparation of SSZ-35 using various conformationally constrained aza-polycyclic ring systems as structure directing agents (SDAs), including 3,3-dimethyl-3-azonia-7-methyl-7-aza-bicyclononane, N-ethyl-N-methyl-9-azoniabicyclo[3.3.1]nonane, and 1,3,3,8,8-pentamethyl-3-azoniabicyclo[3.2.1]octane.
Japanese Patent Publication No. 2002-137918 discloses the synthesis of SSZ-35 using a cis,cis,cis-N-methyl hexahydrojulolidinium cation as a structure directing agent.
However, these SDAs are complex and costly, which makes the synthesis of SSZ-35 using these SDAs complex and costly. This cost can limit the usefulness of SSZ-35 in commercial processes. Thus, it would be desirable to find a way to synthesize SSZ-35 without having to use these SDAs.
It has now been found that SSZ-35 can be prepared using a N,N-diethyl-2,3-dimethylpiperidinium cation or a N,N-dimethyl-2-isopropylpiperidinium cation as a substitute for these complex and costly SDAs.